Wood fan ring



Nov. 13, 1956 HUM/7 1 6/4/77/74/17 John do/dsm/f/r N V EN TORS A TTOR/Vf Y5 13, 1956 H. E. GRANTHAM ET AL 2,770,413

WOOD FAN RING 4 Sheets-Sheet 2 Filed Feb. 1, 1952 INVENTORS ATTORNEYS Nov. 13,1956

H. E. GRANTHAM ET AL WOOD FAN RING 4 Sheets-Sheet 3 Filed Feb. 1, 1952 INVENTOR.

BY M

Mm mw ML an h 0 5 A TTOR/VEKS 13, 1956 H. E. GRANTHAM ETAL 2,770,413

wooo FAN RING Filed Feb. 1, 1952 4 Sheets-Sheet 4 //u /an E. 6/0/7 T770777 United States Patent Wool) FAN RING Hulan E. Grantham and John L. Goldsmith, Houston, Tex., assignors to Hudson Engineering Corporation, Houston, Tern, a corporation of Texas Application February 1, 1952, Serial No. 269,562

19 Claims. (Cl. 230-133) This invention relates to improvements in fan rings and refers particularly to fan rings used-in conjunction with large fans employed in induced draftapparatus for use in installations such as, for example, cooling towers used in cooling water for industrial uses. This application is a continuation-in-part of Serial No. 177,398 filed August 3, 1950, now abandoned.

Conventional cooling towers employ fans having indi vidual fan blades as long as 7 to 10 feet or even longer resulting in a fan that may turn through a diameter as high as 20 feet. Maximum efficiency is achieved by utilizing fans in which the blade tips during operation will remain a constant distance from the inner wall of the fan ring with a minimum of clearance of the inner wall of the fan ring and the fan blade tips.

As a general rule, conventional fan rings for such large fans have been cast or fabricated of metallic segments which, after transportation to the installation site, have been welded, riveted or otherwise fitted together. The metallic segments usually are quite large and frequently become distorted or warped during the shipping and assembling operations, making it extremely difiicult to design and install rings that achieve the desired true cylindrical form and minimum clearance. Furthermore, the prior art structures are usually quite heavy and expensive because of the metallic construction employed necessitating considerable bracing of the cooling tower on which they are used. In addition, the fabrication of the metallic portions have proved to be quite expensive; shipment of the metallic parts also adds considerably to the final cost of the equipment.

Where wood has heretofore been used in making fan i rings, they have not been satisfactory because the vibrations quickly tore them apart, after loosening the nails and screws employed to hold them together.

An object of this invention is to provide a fan ring constructed of wood that may be readily and economically assembled and dismantled at the installation site in substantially true cylindrical form and which will retain its sturdy, reinforced, and comparatively flight, yet because of the unique manner of prefabricating and assembling same without the use of nails or other semi-permanent joining means, is readily fabricated, simple tostore or ship to the installation site and is not adversely affected by vibrations in use.

A further object is toprovide a composite fan ring made of prefabricated, jointed sections that are simple to assemble and adjust for accurate sizing, thathave high lateral stability and rigidity, and that retain these characteristics when subjected the fan is in operation;

Still another object is to constructa fan ring of wood in order to form segments that may be accurately-and to considerable vibration when easily pro-sized which eliminates the need of welding me- 2,770,413 Patented Nov. 13, 1956 "ice tallic parts and avoids the possibility of distortion common in conventional metal rings.

Yet another object is to provide an assembly that provides uniform clearance between the fan ring and the tips of the fan blades.

A further object is to disclose a Wooden fan ring including at least one panel that may be readily removed for inspection of the ring, fan or otherequiprhent.

Another object of this invention is to provide a fan ring adapted to have its height easily variable by the simple addition or subtraction of structural components of which many can be substantial duplicates of those employed to form the basic ring thereby eliminating the fabrication of many special components for rings of various heights.

Other and further objects of this invention will become apparent from a reading of the following description and claims taken in conjunction with the accompanying illustrated embodiments.

In accordance with this invention it has been found that many of the objections to the prior art types of construction may be overcome by utilizing wood in constructing the fan ring and fan ring frame in jointed sections. The wooden sections are shaped to achieve uniformity of size and a minimum number of diiferent sizes or parts. In addition, for a given weight of material, the wooden bracing members are extremely effective in preventing dis- .tortion of the assembled unit. These advantages, coupled with the low initial cost of the raw material and the low cost of fabricating the various portions, provides a struc' ture thatovercomes many of the disadvantages of the prior art.

In the accompanying drawings which. form a part of i this specification:

Fig. 1 is a view in elevation of a fan ring embodying this invention;

Fig. 2 is a Fig. 1;

Fig. 3 is a fragmentary sectional view, on an enlarged scale, taken along the line 33 of Fig. 2 in the direction of the arrows;

Fig. 4 is a sectional View taken along the line 4-4 of top plan view of the fan ring shown in Fig. 3 in the direction of the arrows;

Fig. 5 is a sectional view taken along the line 5--5 in Fig. 3 in the direction of the arrows;

Fig. 6 is a view taken along the line 6--6 in Fig. 2 in the direction of the arrows;

. of this invention; and

Fig. 12;is a fragmentary view of a base plate. adapted .to be employed with this invention- Referring to the drawings and particularly to Fig. 1, the fan ring is seen to comprise an upper, susbtantially -cylindrical shell 10 andaloweryflared portion 11 supported by a suitable outer frame. The fan ring is made up of a series of sections including vertically extending support means and horizontally positioned retaining rings secured'together between the vertical support means. The

on ring maybe supported by any suitable substructure .such as a deck of a cooling tower or the like,'n0t shown in the drawings. While the fan and its moun ting are omitted from the drawings in the interest of simplicity,

r it will be-understood that these members are'used in accordance with conventional practice, the axis of rotation of the fan and the axis of the fan ring being in alignment.

The support frame includes upper and lower retaining rings 16 and 20, respectively, each of which is formed of a plurality of segments such as 8 and 9, respectively, having arcuate inner edges such as 18. Vertical supporting elements or planks 14 extending radially outwardly from and positioned at spaced intervals around shell are arranged between adjacent segments. The top edges of elements 14 may be seated in grooves 17 formed on the under, joining edges of segments 8 while the ends of segments 9 fit into oppositely disposed, horizontal seating means or grooves 21.

Shell 10 of the ring comprises a plurality of staves 12 each having a vertical length substantially greater than the horizontal width and of a small thickness. The staves are arranged in snug side-by-side relationship. Each vertical edge 13 may be joined to the edge of an adjacent stave by tongue and groove joints or other means to achieve the desired snugness and air tightness.

Confronting circular grooves 31 and 32 formed in rings 16 and 20 adjacent the inner, arcuate edges 18 receive the ends of the staves 12 forming shell 16 and provide means carried by the rings for retaining the staves. Vertical edges of elements 14 lie adjacent the outer face of shell 10 and preferably butts up against it.

If desired, additional bracing of the shell and frame may be achieved by adding at least one bracing ring, such as 22, between the top and lower retaining rings. The bracing ring, having a circular inner edge facing the outer wall of shell 10, may comprise a plurality of segments, the ends of adjacent segments being disposedin opposite, horizontal grooves such as 23 in elements 14.

The bottom retaining ring 24 likewise is formed from a plurality of horizontally extending segments having inner, arcuate edges 18 which form a ring having adiameter somewhat greater than those of rings 16 and 20. The ends of the segments may be joined and include grooves to receive the bottom edges of elements 14 as shown in conjunction with ring 16. On the other hand, as shown, the bottom segments may be disposed between adjacent elements 14 with opposite ends of each segment facing the opposite bottom sides of vertical supporting elements 14. The ring 24 may be bolted or otherwise secured to a deck or the like of a cooling tower or other installation.

The lower, flared portion 11 of the fan ring comprises a plurality of quadrilaterally shaped panels 25. Each panel, is made up of a plurality of horizontally extending staves arranged in snug side-by-side relationship and may have tongue and groove joints between adjacent staves. The staves may be similar in shape to staves 12.

Each vertical support element 14 includes lower edges 26 slanting downwardly and outwardly "from the bottom of shell 10. Means as straight grooves 35 and 36 may be formed in opposite sides of each element 14, adjacent the slanting edge 26, such that confronting grooves may receive opposite sides edges of the staves of panels 25. The grooves 35 and 36 may have angled walls with respect to-the faces of elements14, or may be otherwise adapted to permit the panels to assume a flared position in relation to the radially extending, vertical support members. In addition, means such as straight grooves 33 are formed in the bottomfaces of segments 9 of ring and straight grooves 34 are provided in the top face of the segments of ring 24. These grooves are adjacent edges 18 of the" segments and meet slanting grooves 35 and 36. The walls of grooves 33 and 34 are slanted to receive the top and bottom edges. of the panels 25 thereby achieving the downwardly, outwardly flared position of each panel and at the same time supporting each panel on all four sides. The flaring panels in effect form a surface of a frustrum of a polygonal pyramid.

Section 27 of the ring is designed to be easily removed 1 -as a unit in order to permit facility in'inspecti'on of the 4 fan and related parts. The construction of this section is similar to the other sections in every respect with the exception that vertical support members 28 and 29, having shapes and functions identical to support planks 14, are built to face one another, all horizontal segments equivalent to 8, 9 and 22 and panel 25 being fitted into vertical supports 28 as previously described. The vertical staves 12 positioned in section 27 may be arranged to be removed as a unit with the section. This whole section 27 may thus be removed without disturbing the remainder of. the fan ring.

The wooden segments making up the retaining rings and the horizontal bracing means may be secured to the vertical supports 14 by means of stud bolts. For example, stud bolt 41 is shown in Fig. 4 to extend through annular, horizontal openings in element 14 near the bottom edge thereof and through like connecting openings adjacent the outer edge of segments 24 and 38 of the bottom retaining ring. Annular openings 39 and 40 extending vertically through each segment and intersecting the ends of horizontal openings in the segments provide space for securing stud 37 at each end by means of nuts. Stud bolts 42 and 43, respectively, connect segments 9 and 8 to each other through vertical supp0rts.14.

Stud 44' used for connectingadjacent horizontal brace members 22 and securing same to vertical supports 14 is arranged similarly as shown in Fig. 5. Stud 44 extends through horizontal, annular openings 45 positioned in the ends of members 22 fitting into grooves 23. These openings connect with vertical annular openings '46 of sufficient size to permit engagement of nuts 47 on the end of stud 44.

In assembling a particular section, the stud is first centered in one of the annular openings extending through the vertical supporting means 14. Adjacent segments of the retaining rings or of the horizontal brace members are then fitted into their respective grooves with the horizontal annular openings receiving the free ends of the studs. Nuts may then be inserted in the vertical openings, screwed on opposite ends of the studs, and tightened to anchor the bolts in the ends of the retaining ring segments or brace members and to secure these segments and members within the receiving grooves.

The stud arrangement shown in Fig. 6 is typical of that used for connecting removable section 27 to the frame. Stud 48 extends through annular openings 49 and 50 in vertical supporting means 2 3 and 29 and through like annular openings 45 centered horizontally in adjacent ends of opposite brace members 22. It will be noted that brace member 22, comprising an integral part of the assembled frame, includes an extension of annular opening 45, shown by the numeral 50, on the opposite side of opening 46. This extension is adapted to receive the nut-free, stud bolt 48 when section 27 is to be removed from the ring. Thus, when section 27 is to be removed for inspection purposes, the nuts are removed from each bolt securing ring segments, the bolts are pushed into the horizontal opening extensions away from the section until the ends thereof clear the outside faces of the opposite vertical supports of section 27, and the section may then be removed.

Referring now to Figs. 7 through 12, there is illustrated a fan ring employing the principles of this invention and quite similar to that illustrated in Fig. 1 except that it includes an extension or chimney which has the basic fan ring illustrated in Fig. 1. Thus it is possible to extend the height of the fan ring illustrated in Fig. 1 without providing a great many specially constructed parts and the height of the fan ring can be easily increased or decreased by simply adding or taking away their ends in grooves 65 in such planks.

Lai /"0,415.

parts. With such construction, it is possible to increase the height of the fan ring to better direct the moistureladen air exhausted from the cooling tower upwardly a sufiicient distance to prevent any substantial recirculation of the same through the tower.

Though most of the parts shown in Figs. 7 through 12 are numbered differen-tly from similar parts shown in Figs. 1 to 6, the identity of the parts will be apparent to one skilled in the art. j

Referring particularly to Figs. 7,8 and 9, the fan ring is seen to comprise an upper, substantially cylindrical shell 50 and a lower flared portion 51 supported by a suitable outer frame. The support frame, includes a. plurality of annular concentric retaining rings 52, 53a, 53b; 53c and 53d. These rings are at least three in number and are vertically arranged. one above the other. Each comprises a plurality of segments 54 having arcuate inner edges as at 541;. Vertical supporting elements or planks are arranged to extend radially outwardly from and are positioned at spaced circumferential intervals around shell 50 so as to be positioned between adjacent segments 54. These planks include a lower portion 55, similar to plank 14 of Fig. 1, and an upper portion 56 which may be bolted to the lower portion as at 56a. The segments of rings 53b through 53dhave their ends received in grooves in the side faces of adjacent plank portions 56. Each of segments 54 of retaining ring 53:: has one of its ends fitted into a groove formed in upper plank portion 56 and its other end fitted into a groove 58 formed at the upper end of lower plank portion 55. A e r Confronting circular or arcuate grooves 59 formed in opposing faces of the various retaining rings 52, 53a through 53d, adjacent the inner arcuate edges thereof are adapted to receive staves 60 and thereby provide means carried by the rings for receiving and retaining the staves in much the same manner as illustrated in Fig. 3. Staves 60 likewise are arranged in snug side-by-side relationship and can have tongue and groove joints orother joint sealing means between themselves. .Staves 60 have end portions cut away to provide a lip 61 adapted to seat in groove 59. j

The uppermost circumferential fiight of staves 62 have their lowermost ends engaged by the uppermost annular retaining ring 53d, such as by lip 61a engaging groove 59a in the ring, and are retained in place by a suitable re taining means, preferably by the combined action of ring 63 forming a back-up member and a topring member 66. Back-up ring 63 is situated above the uppermost retaining ring 53d and is comprised of a plurality of segments 64 which are arranged between and secured to the upright supporting elements or planks by the receipt of The internal periphery of segments 64 is arcuate or circular in contour so that the segments are adapted j to be in abutting relationship with the outer surfaces of the upwardly extending staves 62'. Disposed at the upper end ofthe staves is a top ring member 66 which has a part 67 engaging the upper ends of staves62 so as to maintain them abutting back-up member segments 64, The top ring can be formed to be angular in cross-section, such as in an angle iron, and is of such size that the outer face of part 67 is the same diameter as the diameter of theinner faces of the staves. In this manner, the upper ends of staves 62 are prevented from displacementinwardly of the fan ring and their outward displacement is prevented by the back-up ring 63 along with the supporting action given by upper plank portion 56. e

As indicated above, top ring member 66 can be formed of a length of suitable angle iron whichhas been bent into circular configuration aud which can be in a plurality of segments, for ease ofshipment and manipulation. These segments can be joined together to form aring by the joining means shown in Fig. 11 which comprises a cleat' plate 68 joined, as by welding, to one end of a segment and bolted by bolts 69 to an adjacent end of another segment. a H U As indicated above, the lower portion of the ring illtistrated in Figs. 7, 8 and 9 is quite similar to that of Fig. 1. Thus, as in Fig-1, additional bracing of the shell and frame can be achieved by adding at least one bracing ring; such as 70, spaced between retaining rings 52 and 53a. The bracing ring has a circular inner edge facing the outer wall of shell 50 and can comprise a plurality of segments, the ends of the segments being disposed in opposite horizontal grooves 71 (Fig. 10) in adjacent ones of elements 55.

The bottom retaining ring 72 can, as in ring 24 of Fig. 1, be formed from a plurality of horizontally ex tending. segments having inner arcuate edges which form a ring having an inner diameter somewhat greater than that of the rings disposed thereabove. The ends of adjacen t. segments can be joined and include grooves to receive the bottom ends of element 55. As a feature of this invention, ring 72 can be disposed upon an annular metal ring 73 having a horizontal plate portion 74 adapted to extend under ring 72 and a plurality of upwardly extending cleat portions 75 which are spaced to be r adiallyjopposite and outward from elements 55 Ito prevent the lower ends of the latter from skidding outwardly of the fan ring. In this manner, there is provided means for preventing elements 55 from being displaced from their proper position.

:Igr o o ves 35 and 36 illustrated in Fig. 4 and are thus adapted to permit panel 76 to assume a flared position in relation to the radially extending 1 vertical support members. Additionally, grooves 79 and 80 can be formed in rings 52 and 72 respectively to receive the sides of the panel members. j

The end of the segments of rings 52, 53a through 54 1, 70 and 72 can be joined to the upright supporting elernentsnor planks by suitable bolt arrangements as illustrated in Fig. 5 for segments 22 of Fig. 1. Thus studs 78 can be provided in the same manner as studs 45 in Fig. 5 to extend horizontally from one end of a segment adjoining a vertical plank portion 55 or 56 into an end of another segment also adjoining a plank portion and can in Fig. 1 is provided for the fan ring illustrated in Fig. 7 ;so that ready access could be had to the inner portion of the ring. Thus one segment of the basic fan ringis doubleplanked by providing planks 55a abutting their faces against two adjacent planks 55. Also a segment 54a j is provided abutting a segmentof ring 53a. Segment 54a 60 ,this removable section while the staves immediately over is of course grooved to receive the staves disposed in thissecti n are received in a groove in the upper facejof the segment of ring 53a which abuts segment 54a. The

segments of the removable section and adjoining sections can be bolted together in the same manner as described with respect to Fig. 6.

While the ends of staves 60 and 62 in Fig. 9 have been shown to be formed into lip 61, it is to be understood that they can be formed in the manner illustrated for staves 12 in Fig. 3 so that the entire ends can be received in a groove. Likewise the ends of the staves. 12 in Fig. 3 can be formed as in Fig. 4 to have only lips on their ends received in a groove.

It will be apparent from the foregoing that the staves 60 can all be made alike and the number or flights'dr "sothat' as many flights of the ring can be provided as desired without fabricating differently shaped. ring parts. Also should a fan ring formed as in Fig. 1 be first placed on atower and then it be learned that an extension should be added thereto, it will merely be necessary to bolt upper plank portions 56 to the lower plank portions 14 as shown in Fig. 1. and to replace ring 8 withring53a. Of course,

:the'segments of ring 8 can be moved upwardly" to form segments of rings 53b through 53d.

The dimensions of the various supports and brace members as well as of the slats are not particualrlycritical and will depend on such factors as strength, weight and size to be achieved. Moisture and fungi resistant woods as redwood and cypress are usually preferred, although the'composite ring and frame or various parts thereof J may be treated chemically or coated with protecting materials to prevent deterioration.

' Many advantages are to be obtained by using, the substantially. all-wood construction of this invention for a fan ring. The elements of the ring may be accurately pre-sized and are not subject to distortion as experienced in metal members. Permanent securing means suchas welded joints, rivets and the like are not needed and nails need not be relied upon; thus, the structure is readily assembled and dismantled. These advantages, coupled with the inherent lightness, strength, and resist'ance'to deteriorationof wood and the unique manner of forming the ring and frame, give a composite fan ring of great strength and high'rigidity capable, of withstanding appreciable vibration over prolonged periods of use. p I .f From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove 'set forth, together with other advantages 5 This is contemplated by and is isto be understood that all matter herein set forth or shown in the accompanying drawings is to be int t ere as .illustrative and not in a limiting sense. The invention having been described, what is claimed 'l.'A' fan ring constructed substantially of wood comprising a frame including upper and lower annular concentric retaining members, each made up. of a plurality of "segments; upright supporting elements arranged in I.circumferentially spaced positions about the ,members with one between adjacent segments of each retaining member; separate hold fast means providing the. prin cipal means of securing adjacent segments 'rigidly to each other and to an upright supporting element therebetween independently of the other similar joints of the fan ring; a plurality of staves; and stave receiving and retaining means carried by the retaining memberslfor receiving and retaining the staves between said. members in snug, upright, side-by-side relationship in the form of a substantially cylindrical shell. I v, v 2. A'fan ring as in claim lwherein the separate hold fast means are bolts extending through the upright elements with their ends anchored in adjacent segments of the members;

'3. fan ring as in claim 1 wherein the' uprightelements'are planks arranged with their width dimensions disposed substantially radially of the retaining members and with seat means on each side for receiving'the ends of adjacent segments. g 1

4. A fan ring constructed substantially of wood comprisinga frame'including top and lower annular concen-.

tric retaining members, each made up of a plurality of segments; upright supporting elements arranged in circumferentially spaced positions about the members with one between adjacent segments of each retaining memberysp'arate hold fast means releasably anchored .to each pair of adjacent segments and urging adjacent segments toward each other to clamp an upright supporting element therebetween and provide the sole means of rigidly securing together adjacent segments and the supporting element therebetween independently of the other similar joints of the fan ring; said members formed with confronting circular grooves; and a plurality of staves arranged in snug, side-by-side relationship to form a substantially cylindrical shell, the top and bottom ends of the staves being disposed in the grooves. 1

5. A fan ring in accordance with claim 4 in which at least one horizontal bracing ring is positioned between the top and lower retaining members, said bracing ring formed of a plurality of segments, said segments being arranged between and secured to each other and to said vertical supporting elements in the same manner as the segments of the retaining members and having their inner peripheries abutting the outer surfaces of the staves offthe shell to additionally support the staves.

6. A fan ring as in claim 4 wherein the separate hold fast means are bolts extending through the upright elements, with their ends anchored in adjacent segments of f the members.

7. A fan ring as in claim 4 wherein the upright elements are planks arranged radially with seatmeans on each side for receiving the ends of adjacent segments of the retaining members.

8. A fan ring constructed substantially of wood comprising a frame including top, lower and bottom annular concentric retaining rings, each'formed of a plurality of segments; vertical supporting planks arranged in circumferentially spaced positions about the rings with one between adjacent segments of each ring to which the segments are secured, said planks having their width dimensionextending radially; said top and lower rings formed with confronting circular grooves adjacent their inner edges; a plurality of staves vertically arranged in snug,

V side-by-side relationship to form a substantially cylindrical shell, the top and bottom ends of the staves being disposed in the confronting circular grooves; said planks formed with confronting straight grooves slanting downwardly and outwardly along their inner edges and below the lower ring; a plurality of outwardly flaring panels disposed in the confronting straight grooves between adjacent upright planks, and the top and bottom edges of the panels engaging the lower and bottom retaining rings respectively.

9. A fan ring as in claim 8 wherein bolts extend through the supporting planks with their ends anchored in adjacent segments of the retaining rings to secure the segments to the planks. V

10. A fan ring as in claim 8 wherein the planks are arranged radially and have grooves on their sides, extending substantially horizontally, for receiving the ends of adjacent segments of the lower and bottom retaining rings.

ll. A fan ring as in claim 8 wherein two supporting planks are placed together in a pair in each of two adjacent positions, and means for removably securing the planks of each pairtogether whereby one plank from each of said pairsmay be removed and still leave supporting planks for the ends of the retainer ring segments residing adjacent the removed planks, to provide ready access to the interior of the fan ring.

12. A'fan ringas in claim 8 in which at least one horizontal bracing ring is positioned between the top and lower retaining rings, said bracing ring being formed of a plurality of segments arranged between and secured to the vertical supporting planks, the inner periphery of the bracing ring abutting the outer surfaces of the staves of the shell to additionally support the staves against outward collapse.

13. A fan ring constructed substantially of wood comprising a frame including top, lower and bottom annular concentric retaining rings, each formed of a plurality of segments; vertical supporting planks arranged in circumferentially spaced positions about the rings with one between adjacent segments of each ring to which the segments are secured, said planks having their width dimension extending radially; said top and lower rings formed with confronting circular grooves adjacent their inner edges; a plurality of staves vertically arranged in snug, side-by-side relationship to form a substantially cylindrical shell, the top and bottom ends of the staves be ing disposed in the confronting circular grooves; said planks formed with confronting straight grooves slanting downwardly and outwardly along their inner edges and below the lower ring; a plurality of outwardly flaring panels made up of horizontally arranged staves in snug, side-by-side relationship, said staves having their ends disposed in the confronting straight grooves between adjacent upright planks, and the top and bottom edges of the panels engaging the lower and bottom retaining rings respectively.

14. A fan ring constructed substantially of wood comprising a frame including top, lower and bottom annular concentric retaining rings, each formed of a plurality of segments; vertical supporting planks arranged in circumferentially spaced positions about the rings with one between adjacent segments of each to which the segments are secured, said planks having their width dimension extending radially; said top and lower rings formed with confronting circular grooves adjacent their inner edges; a plurality of staves vertically arranged in snug, side-byside relationship to form a substantially cylindrical shell, the top and bottom ends of the staves being disposed in the confronting circular grooves; said planks formed with confronting seating means slanting downwardly and outwardly along their inner edges and below the lower ring; a plurality of outwardly flaring panels disposed in the confronting seating means between adjacent upright planks, and the top and bottom edges of the panels engaging the lower and bottom retaining rings respectively.

15. A fan ring constructed substantially of wood comprising at least three vertically arranged annular concern tric retaining members, each comprising a plurality of segments; upright supporting elements arranged in circumferentially spaced positions about the members with one between adjacent segments of each retaining member; separate hold fast means providing the principal means of securing adjacent segments rigidly to each other and to an upright supporting element therebetween independently of the other similar joints of the fan ring; a plurality of staves; and stave receiving and retaining means carried by the retaining members for receiving and retaining staves between adjacent members in snug, upright, side-byside relationship to form a substantially cylindrical shell.

16. The fan ring of claim in combination with stave receiving and retaining means carried by the uppermost retaining member to receive and retain staves extending upwardly of said uppermost member, staves in said receiving means, a back-up ring above said uppermost ring, said back-up ring formed of a plurality of segments, said segments being arranged between and secured to said upright supporting elements and having their internal peripheries abutting the outer surfaces of said upwardly extending staves, and a top ring member having a part engaging the upper ends of said upwardly extending staves to maintain them abuting said back-up ring.

17. The fan ring of claim 16 wherein said stave receiving and retaining means are grooves adapted to receive the ends of said staves.

18. The fan ring of claim 17 wherein bolts extend through the upright elements with their ends anchored in adjacent segments of said retaining members.

19. A fan ring constructed substantially of wood which comprises a plurality of concentric retaining ring including a bottom ring and at least three superior rings arranged vertically thereabove, each formed of a plurality of segments; vertical supporting planks arranged in circumferentially spaced positions about said rings with one between adjacent segments of the superior rings to which said adjacent segments are secured; said superior rings formed with confronting arcuate grooves adjacent their inner edges; a plurality of staves vertically arranged in snug, side-by-side relationship and in circumferential rows between adjacent superior rings to form a substantially cylindrical shell, the top and bottom ends of the staves being disposed in said confronting arcuate grooves; panel engaging means carried by said planks and slanting downwardly and outwardly along the inner edges of the planks and below the lowermost superior ring; a plurality of outwardly flaring panels engaged by said adjacent upright planks by said panel engaging means, the top and bottom edges of the panels engaging the lowermost of the superior rings and said bottom ring respectively; the uppermost of said superior rings having an arcuate groove in its upper face; a plurality of upwardly extending staves arranged in snug side-by-side relationship with their bottom ends in last said arcuate groove; a back-up ring above said uppermost ring, said back-up ring formed of a plurality of segments, said segments being arranged between and secured to said vertical planks and having their internal peripheries abutting the outer surfaces of said upwardly extending staves, and a top ring member having a part engaging the upper ends of said upwardly extending staves to maintain them abutting said back-up ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,125,249 Archer Jan. 19, 1915 1,145,306 Griflin July 6, 1915 1,168,886 Hulen Jan. 18, 1916 1,178,641 Henkel Apr. 11, 1916 2,466,827 Roth Apr. 12, 1949 2,524,390 Lau Bach et al. Oct. 3, 1950 2,557,878 Lankenau June 19, 1951 FOREIGN PATENTS 649,284 France July 2, 1927 

